Complex interfacial flows with heat transfer: Analysis, direct numerical simulations and experiments

多相流通常在工程中起着核心作用，并有许多实际应用。拟议的研究重点是自由表面薄膜流加热基板。这种流动是界面流动的一般类别的一部分，界面流动涉及诸如色散和非线性、耗散和能量积累、二维和三维现象等不同的效应，因此它们具有重要的基本意义。膜动力学和稳定性受重力、惯性、毛细作用、热毛细作用、粘度以及表面拓扑结构和条件的影响。热毛细力引起了一种重要的表面现象，称为马兰戈尼效应，其中由于温度引起的表面张力变化导致液体流动。马兰戈尼效应导致薄膜变形，驱使它局部上升，从而产生不稳定性，最终导致波结构的形成。在低雷诺数（Re）数加热降膜的热毛细力的竞争与重力和粘度。在剪切驱动的水平流中，重力不存在，驱动力是气液界面处的粘性剪切力。在较高Re时，惯性开始起越来越大的作用。薄膜流在其热交换能力方面显示出很大的希望。我们渴望利用和扩展这一承诺，这将使一系列关键依赖于薄膜流动的技术和工业应用的性能和效率得到逐步改善。该提案旨在为一项为期三年的综合研究计划提供资金，该计划将三管齐下的新实验，理论和数值研究，旨在合理理解和系统预测流过加热表面的液膜的流体动力学特性，以及这些特性如何控制相应流动的传热潜力。该提案旨在回答这些问题，目标是能够准确有效地预测复杂的物理行为。我们专注于两个范式流：重力驱动的下降膜和气体驱动的水平膜。分析工作将通过详细的数值模拟来补充，这些模拟将用于验证所开发的流动模型的有效性，同时将分析和计算与先进的实验进行对比。这项工作将由伦敦帝国理工学院化学和机械工程系的一个小组进行，他们具有互补的技能和优势：Kalliadasis（分析-理论），Markides（实验流体力学）和货车Wachem（多相流模型-计算）。

Multiphase flows often play a central role in engineering and have numerous practical applications. The proposed research focuses on free-surface thin-film flows over heated substrates. Such flows are part of the general class of interfacial flows which involve such diverse effects as dispersion and nonlinearity,dissipation and energy accumulation, two- and three-dimensional phenomena and hence they are of great fundamental significance. Film dynamics and stability are governed by the effects of gravity, inertia, capillarity, thermocapillarity, viscosity, as well as surface topology and conditions. The thermocapillary forces give rise to an important surface phenomenon known as the Marangoni effect, in which variations in surface tension due to temperature result in liquid flow. The Marangoni effect leads to film deformation, driving it to rise locally and thus to generate instabilities that lead eventually to the formation of wave structures. In low-Reynolds (Re)-numbers heated falling films the thermocapillary forces are in competition with those of gravity and viscosity. In shear-driven horizontal flows, gravity is absent and the driving force is that of viscous shear at the gas-liquid interface. At higher Re inertia begins to play an increasingly dominant role.Film flows show great promise in terms of their heat exchange capabilities. We aspire to harness and extend this promise, which will allow step improvements to the performance and efficiency of a host of technologies and industrial applications that rely crucially on film flows. This proposal seeks funding for a comprehensive three-year research programme into a three-pronged novel experimental, theoretical and numerical investigation aimed at rationally understanding and systematically predicting the hydrodynamic characteristics of liquid films flowing over heated surfaces, and furthermore, how these characteristics control the heat transfer potential of the corresponding flows. The proposal aims to answer these questions, with the goal of being able to accurately and efficiently predict complex physical behaviour inheated film flows. We focus specifically on two paradigm flows: gravity-driven falling films and gas-driven horizontal films. The analytical work will be complemented by detailed numerical simulations that will act to verify the efficacy of the developed flow models while both analysis and computations will be contrasted with advanced experiments. The work will be undertaken by a team from the Chemical and Mechanical Engineering Departments at Imperial College London with complementary skills and strengths: Kalliadasis (Analysis--Theory), Markides (Experimental Fluid Mechanics) and van Wachem (Multiphase Flow Modelling--Computations).